Therapeutic benefits can be achieved in some instances by providing a bioactive agent to a specific target tissue, instead of systemically. This is because the effect of the agent on the target tissue can be maximized while the side effects on other tissues can be minimized. Therapeutic benefits can also be achieved by providing a bioactive agent to a subject in a manner that provides controlled release of the bioactive agent. Controlled release of a bioactive agent can allow the concentration of the bioactive agent at the target tissue site to remain at a more consistent therapeutic level.
One technique for providing controlled-release site-specific drug delivery is to use a bioactive agent-eluting coating system disposed on a medical device. The coating can serve to control the rate at which the bioactive agent is eluted. In addition, because the coating is disposed on a medical device and because the medical device can be positioned as desired within the body of a patient, the delivery of the bioactive agent can be site-specific.
Some types of bioactive agents, however, may be difficult to regulate when provided in the form of an bioactive agent-eluting coating system. Notably, it is difficult to regulate the elution rate of hydrophilic bioactive agents from polymeric coating systems. Accordingly, there is a need for polymeric coating systems that can effectively control the elution rate of hydrophilic bioactive agents.